The Cardiovascular System 1.1 Flashcards
What does the vena cava do?
Brings deoxygenated blood back to the right atrium
What is the cardiac conduction system?
A group of specialised cells located in the wall of the heart which sends electrical impulses to the cardiac muscle causing contractions
What does the pulmonary artery do?
Leaves the right ventricle with deoxygenated blood to go to the lungs
What does the pulmonary vein do?
Delivers oxygenated blood to the left atrium
What does the aorta do?
Leaves the left ventricle with oxygenated blood leading to the body
What are the functions of valves?
- They close to prevent backflow of blood
- Make sure blood flows in one direction
- They open to allow blood to pass through
What is the role of the AVN node in the cardiac conduction system?
- The AVNode delays the SA node’s electrical signal. Delays the signal by a consistent amount of time (a fraction of a second) each time.
- Delay ensures that your atria are empty of blood before the contraction stops. (atria are the heart’s upper chambers)
What are the 4 main valves of the heart?
Tricuspid valve
Bicuspid valve
Semi-lunar valves
Where is the tricuspid valve located?
Between the right atrium and right ventricle
Where is the Bicuspid valve located?
Between the left atrium and left ventricle
What is the septum?
A wall of tissue separating the hearts left and right sides
Where are the semi- lunar valves located?
Found between the right and left ventricles
Pulmonary artery
Aorta
In what order the the cardiac conduction system occur?
SAN - Atrial systole - AVN-Bundle of HIS -Purkinje fibres - Ventricular systole
(Sally always aims balls past vicky)
What are chemoreceptors?
Chemoreceptors sense chemical changes
Found in carotid arteries & the aortic arch
During exercise chemoreceptors detect an increase in carbon dioxide
Role of CO2 is important in controlling heart rate
Increased concentration of CO2 in the blood will have effect of stimulating the sympathetic nervous system meaning the heart will beat faster
How does an increase in carbon dioxide in the blood during exercise lead to an increase in breathing rate?
- Detected by chemoreceptors
- Impulse sent to the respiratory centre/medulla
- Increased impulse to respiratory muscles to contract faster
How can the cardiovascular drift result in lower levels of performance?
- Athletes will sweat-reducing plasma of blood
- Blood becomes more viscous (thicker) reducing venous return
- As stroke volume /ejection fraction decreases heart rate increases to maintain cardiac output
What is the venous return?
- The volume of blood reutrning to the heart via the veins
If venous return increases, then stroke volume will also increase
(If more blood enters the heart then more blood goes out)
What are baroreceptors?
Baroreceptors establish a set point for blood pressure
An increase above or decrease below this set point results in baroreceptors sending signals to the medulla in the brain
Contain nerve endings that respond to the stretching of the arterial wall caused by changes in blood pressure
What are Proprioceptors?
Proprioceptors provide information about movement and body position
- At start of exercise they detect an increase in muscle movement
- These receptors then send an impulse to the medulla which then sends an impulse through to the sympathetic nervous system to the SAN to increase heart rate
- However when the parasympathetic system stimulates the SAN heart rate decreases
What is the Neural Control Mechanism?
It involves the sympathetic nervous system- Which stimulates the heart to beat faster
And the parasympathetic nervous system- Which returns the heart to its resting level
Sympathetic nervous impulses are sent to the SAN & there is a decrease in parasympathetic nerve impulses so that the heart rate increases
What 2 parts is the nervous system made up of?
The CNS (brain & spinal cord)
Peripheral nervous system- consists of nerve cells which transmit information to from the CNS
What are both the CNS and Peripheral nervous system co-ordinated by?
Both co-ordinated by the cardiac control centre located in the medulla oblongata of the brain
What is adrenaline?
A stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise causing an increase in heart rate
Results in more blood being pumped to the working muscles so they can receive more oxygen for the energy they need
What is stroke volume?
- The volume of blood pumped out by the heart ventricles in each contraction
Formula for cardiac output?
- Stroke volume x Heart rate
Formula for maximum heart rate?
220 - (your age)
What is cardiac hypertrophy?
- The thickening of the muscular wall of the heart so it becomes bigger and stronger
What is bradycardia?
- A decrease in resting heart rate to below 60 bpm
What is myocardium?
Cardiac tissue
